Synthesis of PVP-protected NiPd nanoalloys by modified polyol process and their magnetic properties

Aqueously dispersed NiPd nanoparticle alloys with various Ni/Pd molar ratios were synthesized by polyol process in the present work. Measurements such as XRD, ICP and TEM were performed to characterize the as-synthesized nanoparticles. The results confirmed the formation of NiPd nanoalloys and not simply mixtures of the two metal nanoparticles. The PVP, which was used as capping agent to stabilize the nanoparticles and prevent them from oxidation or agglomeration, accounted for approximately 30% of the total mass fraction of the nanoparticles. The magnetic measurement revealed the as-synthesized NiPd nanoalloys exhibited ferromagnetic behaviors, and the saturation magnetization as well as heat-generation ability was enhanced with increasing Ni concentration. Upon exposure to an external alternation magnetic field of 60 kHz and 7.5 kA/m, specific power absorption rate (SAR) of the nanoalloy with the composition of Ni63.8Pd36.2 reached 40 w/g, indicating high heat-generation ability.